Princess Mirage happens to be my favorite character in Yuna. ^_^ The most notable thing about her is that her character design was done by Kousuke Fujishima, the creator of "Oh! My Goddess", as a favor to Mika Akitaka (the normal Yuna Character Designer). Notice she looks a lot like Belldandy, only with cool armor and personal point defense sattellites? ^_^

Princess Mirage is similar in many ways to Sailor Saturn. I'm sure I'll learn more details by playing more of Yuna 2: Eternal Princess, but here's what I know at the moment. Princess Mirage is the captain of the ship The Eternal Princess, which is essentially a galactic doomsday failsafe device. Scattered around the galaxy are hidden beacons which were left eons ago to monitor the level of conflict in the surrouding area. If an interplanetary war erupts near one of these beacons, the Eternal Princess will come to stop the conflict from escalating into a devastating galactic war; it does this by completely obliterating the planets which are involved in the conflict. Think of it as a "Death Star of Justice" only a whole lot cooler. ^_- As it so happens, in Yuna 2 Erika has a cat-fight with Yuna right next to one of these beacons, and because they're so close by it signals the Princess to come destroy the Earth. Oops. Luckily it also awakens Yuuri as a sort of PR agent; "We're sorry your planet was erroneously marked for destruction; I will be happy to assist you in rectifying the situation." Basically in Yuna 2 your job is to find and destroy a certain set of Beacons to prevent the Eternal Princess from coming to destroy the Earth.

In Yuna 3 (at least to the point where I've played as of this writing), Princess Mirage only plays a minor role: she supplies one of Yuna's special attacks. ^_^ (And what an attack it is!) As soon as Yuna makes Level 15, the following happens (right in the middle of a battle):